Pressure sensitive adhesives may be used for accomplishing a bond between two articles without the use of solvent, water, and/or heat to activate the adhesive. Applications in which a pressure sensitive adhesive (PSA) may be advantageous include coatings which are sometimes used, for example, in conjunction with protective coverings for electronic screens such as mobile phone screens or LCD monitor screens.
Many current adhesive formulations for use in such applications are silicone based or, if acrylic based, include an isocyanate cross-linking agent that effectively limits the acrylic base to hydroxyl functional acrylics. The use of isocyanates as cross-linking agents has numerous other drawbacks. In addition to restricting the types of acrylic base that can be used, isocyanates have a level of toxicity and can be expensive. Some isocyanates also have some level of coloration that makes them undesirable for use in screen coverings.
Isocyanates, when used as crosslinking agents, also suffer from the drawback that they lack stability at ambient conditions. As a result, current adhesive formulations employing these compounds as cross-linkers are not mixed together until shortly before use, typically leading to an extra processing step onsite at the manufacturing facility where the adhesive is to be applied.
These and other drawbacks are present in current adhesive formulations.